Found crawling across a gravel road. It is not uncommon to find these large silkworm moth caterpillars on trails and roads in late summer, heading off to pupate somewhere. This one was moving quickly so I put it on my hand for a photo, but it didn't slow it down much.

To see an earlier instar of this caterpillar, as well as the huge moth it will become, click here http://www.pbase.com/laroseforest/image/156919233